Hi Russell, On Mon, Mar 19, 2018 at 11:12:05AM +0000, Russell King - ARM Linux wrote: > On Mon, Mar 19, 2018 at 09:52:52AM +0100, Antoine Tenart wrote: > > > > Anyway, the reason to use in-band negotiation was also to avoid using > > fixed-link. It would work but always report the link is up, which for > > the user isn't a great experience as we have a way to detect this. > > > > What would you suggest to achieve this in a reasonable way? > > The intention of this test in phylink_of_phy_connect() is to avoid > failing when there is no requirement for a PHY to be present (such as > a fixed link, or an 802.3z link.) However, with 10G PHYs such as the > 3310, we need the PHY so we can read the speed from it, and so know > whether to downgrade the MAC to SGMII mode, or having downgraded the > MAC, upgrade it back to 10G mode when the PHY switches to 10G. > > I'm guessing that you're wanting this for the DB boards, but I don't > see why. Do they not have PHYs?
You guessed right, that's exactly my use case. The DB boards (7k and 8k) have 10G interfaces without PHYs. I could describe them as fixed-link (it works), but it would be better not to require a PHY in phylink_of_phy_connect() for such interfaces. That's why I used in-band AN, which is wrong, but we still probably need to add a check to allow such setups. I'm all ears for suggestions as I do not have the full picture of all the supported modes and their requirements. Thanks! Antoine -- Antoine Ténart, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com
